The disclosed vulnerability leverages an indirect prompt injection attack targeting Google Gemini, an AI assistant integrated with Google Calendar. Attackers craft malicious calendar invites embedding natural language prompts within the event description. When a user innocuously queries Gemini about their schedule, the AI parses the hidden prompt, which instructs it to summarize the user's private meetings and create a new calendar event containing this sensitive information. This new event is often visible to the attacker due to typical enterprise calendar sharing configurations, enabling data exfiltration without direct user interaction or explicit authorization bypass. The flaw exploits AI behavior at runtime, where language understanding and prompt parsing become attack vectors, rather than traditional software bugs. The attack chain starts with sending a crafted calendar invite, followed by a benign user query that triggers the AI to execute the injected prompt. The vulnerability was responsibly disclosed and patched by Google. This incident underscores the novel security challenges introduced by AI-native features, where prompt injection can circumvent existing authorization guardrails and privacy controls. It also highlights the need for continuous security evaluation of AI systems, including prompt sanitization, context validation, and strict access controls. The broader context includes similar AI-related vulnerabilities in other platforms, emphasizing the expanding attack surface as organizations adopt AI tools for workflow automation.

For European organizations, this vulnerability poses significant risks to confidentiality and privacy of sensitive calendar data, which often includes meeting details, participant information, and strategic discussions. Unauthorized access to such information can lead to corporate espionage, competitive disadvantage, and regulatory compliance violations under GDPR. The ability to create deceptive calendar events without user interaction can also facilitate social engineering, phishing, or operational disruption. Since Google Workspace and Google Calendar are widely used across European enterprises, especially in sectors like finance, technology, and government, the potential for data leakage is substantial. The attack requires minimal attacker privileges—only the ability to send calendar invites—and no direct user action beyond normal AI queries, increasing the likelihood of successful exploitation. This vulnerability also raises concerns about the security of AI integrations in enterprise environments, where AI agents may inadvertently become data exfiltration channels. The incident highlights the necessity for organizations to scrutinize AI-driven workflows and their interaction with sensitive data. Failure to mitigate such risks could result in reputational damage, financial loss, and regulatory penalties.

1. Restrict calendar sharing permissions to the minimum necessary, avoiding broad visibility of calendar events to external or untrusted users. 2. Implement monitoring and alerting for unusual calendar event creation patterns, especially events created automatically or containing sensitive information in descriptions. 3. Apply strict input validation and sanitization on AI prompt inputs, particularly those derived from user-generated content like calendar invites. 4. Limit AI assistant access scopes and privileges, ensuring that AI agents cannot create or modify calendar events without explicit authorization and logging. 5. Educate users about the risks of interacting with AI assistants and encourage cautious behavior when querying sensitive information. 6. Regularly audit AI integrations and service accounts for excessive permissions and enforce the principle of least privilege. 7. Collaborate with vendors to ensure timely patching of AI-related vulnerabilities and request transparency on AI model behavior and security controls. 8. Consider deploying additional security layers such as Data Loss Prevention (DLP) tools that can detect and block unauthorized data exfiltration attempts via calendar or AI channels.